1. Field of the Invention
The present invention relates to an information update count managing method and an information update count managing apparatus for managing the number of times certain information has been updated (hereinafter, “information update count”). The present invention also relates to a contents usage count managing method and a contents usage count storing apparatus for managing the number of times certain contents such as software or a movie have been used (hereinafter, “contents usage count”).
2. Description of the Related Art
Recently, an advanced video compression technique which is called “MPEG2” and an optical disc having a large capacity of about 5 GB which is called “DVD (digital video disc)” have been developed in the art. The combination of the two has enabled high quality digital AV data having a length of 2 hours or more to be recorded on a single DVD. As a result, video contents such as movies can now be enjoyed at home with a high image quality.
In the movie industry, it has been customary to release a new movie at different times in different countries/regions. Taking Hollywood movies for example, they are normally released first in the United States and then in Japan and/or in Europe half a year later. As a result, it is possible to selectively distribute popular movies worldwide based on their performances in the United States, or to have a sufficient period of time to solve ethical problems which may be encountered in playing certain movies in different countries/regions. Particularly, the ethical policies of groups of people depend on their customs and religions and vary from one country to another. A movie that has no ethical problem in one country may have some ethical problems in another country, and therefore one must carefully consider which movies can be released in each country.
In view of this, a DVD and a DVD reproduction apparatus are provided with a mechanism for controlling regions where the DVD can be reproduced. Specifically, a DVD contains information indicating region (s) where the disc can be reproduced, and a DVD reproduction apparatus stores information indicating region(s) where the apparatus can be used.
If the only object to be achieved is to be able to store regional information in the DVD reproduction apparatus, the regional information can be set therein by using a switch (jumper pins, a dip switch, etc.), a non-volatile memory which can be written to only once (PROM), or a non-volatile memory which can be written to as many times as desired (EEPROM).
However, it may be inconvenient if the setting of the regional information is permitted only once, particularly when the user is transferred to a new work location abroad or when the manufacturer wishes to change the destination for export. Conversely, when the setting is permitted an unlimited number of times, the above-described ethical problems arise. In view of this, a DVD system has been designed with an upper limit for the number of times the setting is permitted, whereby the user is permitted to re-set the region of use up to the upper limit. Such a design is typically implemented by employing an EEPROM in which data can be erased/written in a unit of WORDs (e.g., bytes), and storing the regional information which is currently set and the number of times the setting has been done (hereinafter, “setting count”).
However, the technique of simply storing the regional information and/or the setting count in an EEPROM, or the like, has been vulnerable to illegal alterations such as illegally cracking or hacking the regional control. For example, if the location in the EEPROM where the regional information or the setting count is stored is revealed, the setting count value can be altered, whereby the setting is permitted an unlimited number of times. If such an illegal alteration becomes widespread among the consuming public, valuable contents can no longer be distributed, thereby detracting from the benefits to the majority of the users who are properly observing copyrights.
It is also meaningful to set, in addition to the regional information, a contents usage count (“usage” herein includes playing and copying) for controlling the number of times contents such as general software or movies can be used. For example, where the charge for a certain content is determined according to the number of times the user is permitted to use the content, the user can obtain the right to use the content to an extent which is determined based on the amount of charge the user pays. Still, if the usage count control is cracked or hacked by an illegal alteration, the content can then be used an unlimited number of times. In such a case, valuable contents can no longer be distributed, thereby detracting from the benefits to the majority of the users who are properly observing copyrights.